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United States Patent 0 3,479,286 United States Patent 0 ""lC€ Patented Nov. 18, 1969 1 2 with the Underwriters Laboratories (UL) classi?cation 3,479,286 which indicates a decrease in toxicity from class 1 to class FLAME-EXTINGUISHING COMPOSITIONS 6. In class 1, compounds such as sulfur dioxide are in Gian Paolo Gambaretto, Padova, Paolo Rinaldo, Venice, and Mario Palato, Padova, Italy, assignors to Monte cluded Whereas tri?uorobromomethane (CBrF3) is con catini Edison S.p.A., Milan, Italy, a corporation of sidered to be in class 6. Compounds such as carbon tetra Milan, Italy chloride are the most toxic of the haloalkanes (class 3). No Drawing. Filed Sept. 19, 1966, Ser. No. 580,212 TABLE I.—TOXICITY OF HALOALKANES Claims priority, application Italy, Sept. 22, 1965, 21,090/65 Compound: U.L. Class Int. Cl. A62d 1/00 10 C014 ____ __ 3 US. ‘Cl. 252-8 2 ‘Claims CCl3F _______________________________ __ 5a CCI2F2 __ __ 6 CCIF3 ___ _____ 6 ABSTRACT OF THE DISCLOSURE CF, 6 A ?ame-extinguishing composition containing a com 15 CHCI, _____ 3 pletely halogenated alkane, having at least two ?uorine CHCl2F ___ 5 atoms and at least one bromine atom per molecule and a CHClF2 ______________________________ __ 5a ?uorohydrocarbon having at least one hydrogen atom per CHF, ___-.. 6 molecule. The composition can include, optionally, a pro (CHCIB) ____ 3 pellant such as sulfur-hexa?uoride and carbon dioxide. (CC13F)' 5a The molar ratio of the ?uoro-hydrocarbon to the com CH2Cl2 _ ___ 4-5 pletely halogenated alkane ranges between substantially (CHCI2F) ____________________________ __ 5 0.2 and 5. CCI2F2 ___- ____ 6 Our present invention relates to ?ame-extinguishing 25 CBI‘ZFZ ___ 4 compositions containing high molecular weight, low car CBrFs ____ 6 'bon number haloalkanes and, more particularly, to im CClBrF2 ___ 5a proved ?rst-extinguishing compositions containing bro COR 6 minated Freons, i.e. ?uorobromoalkanes and ?uorochloro (CClBrF2) ___________________________ __ 5a bromoalkanes. (OBI-F3) _____________________________ ..._ 6 It is known that ‘brominated ?uoro carbons of the Freon type (i.e. having one or two carbon atoms and 4 CH3Br __ 2 or 6 halogen atoms, primarily bromine and ?uorine) have (CBrF3) _____________________________ __ 6 ?ame-extinguishing properties alone or in combination CH2ClBr __ 3 with other substances. Such compounds may be used as (CClBrF2) ____________________________ __ 5a propellants for liquids or gases and thus imparts a ?ame extinguishing character to the mixture dispensed. Since The use of brominated Freons (e.g. bromo?uorometh these compounds are generally nontoxic or are of low anes) in commercial ?ame-extinguishing compositions and toxicity, they do not possess the disadvantages of such as ?ame-extinguishing agents has heretofore been strictly _ ?ame-extinguishing materials as carbon tetrachloride and 40 limited because of the high costs of these compounds. other chemical compounds which are corrosive or chemi Thus it has been necessary to employ less e?icient ?ame cally react with their environment. extinguishing agents as propellants and the like because of Apparently, the bromine atom or atoms in the molecule economical considerations. provide carbon-bromine bonds activatable at low energies It is, therefore, the principal object of the present in and thus at relatively low temperatures to produce free 45 vention to provide an improved ?ame-extinguishing com radicals which serve as chain-terminating reactants when position of matter with highly e?icien-t ?ame-extinguishing they are involved in the chain reactions of the combustion properties but of relatively low cost. - process. In e?ect, therefore, the ?ame-extinguishing ?uoro Another object of this invention is to provide a ?ame bromoalkanes act as chain-reaction moderators or limiters extinguishing low-cost propellant which is free from the by removing possible reaction participants from the com— 50 disadvantaged characterizing toxic haloalkanes. bustion zone. Another advantage of the use of such com We have found that these objects can be attained with a pounds as ?ame-extinguishing substances is that the rela ?ame-extinguishing composition of matter which com tively high ?uorine content and the proportionally low prises at least one brominated Freon (e.g. a bromo?uoro chlorine content or even the absence of chlorine ensure methane or ethane containing at least two ?uorine atoms that the compound will be su?iciently volatile to be used 55 and at least one bromide atom) in combination with one effectively in the ?ame-extinguishing process at low am or more ?uorochlorohydrocarbons containing at least one bient temperatures and, further, that the ?ame-extinguish hydrogen atom per molecule. It has been discovered, sur ing substance will not break down to poisonous or toxic prisingly, that the combination of a ?uorochlorohydrocar compounds such as phosgene. The high vapor density of bon containing at least one hydrogen atom per molecule these products permits of their use in open spaces since 60 with the bromo?uoroalkane imparts to the ?ame-extin they remain for prolonged periods in the combustion zone guishing combination synergistic effects with respect to the and are not readily dispersed by diffusion. ?ame-extinguishing qualities even though the use of a Furthermore, the bromo?uoro mono and dialkanes and ?uorochlorohydrocarbon of this nature might be thought especially the bromo?uoro methanes and ethanes having to decrease the ?re-extinguishing characteristics because of at least two ?uorine atoms and one bromine atom are 65 its own properties. Furthermore it has been found that characterized by a comparatively low toxicity, particularly the combination (i.e. the combination of at least one com when contrasted with the chloromethanes and ‘bromo pletely halogenated bromo?uoromethane or ethane with methanes (e.g. carbon tetrachloride, methylbromide and at least one fluorochlorohydrocarbon-—containing at least chlorobromomethanes) commonly used heretofore in one hydrogen atom per molecule—-) does not increase the flame-extinguishing compositions. To demonstrate the 70 toxicity of the ?ame-extinguishing system above that to be relative toxicities of the haloalkanes, we list below in expected from the bromo?uorohydrocarbon alone. More Table I the toxicities of various haloalkanes in accordance over, the ?uorochlorohydrocarbon acts as a propellant for 8,479,286 3 4 the brominated Freon and greatly facilitates the use of the position in percent, we have reported also the percentage composition asa ?ame-extinguishing agent. di?ference between the quantity of composition theo Thus the mixture of ?uorochlorohydrocarbons with retically necessary, calculated to extinguish the ?ame on brominated Freon gave rise to compositions with a rela- the basis of the known extinguishing capacity of the sin tively high ?ame-extinguishing e?iciency. gle components, and the quantity which has been found The propelling coadjuvant for the brominated Freon 5 to be actually necessary. TABLE II Composition Lowest concentn, percent in the liquid (mol) phase, ——- ——————— —-————— Dilfcrcnce, Agent percent mol Theoretical Actual percent 1 ________ __ CFzBl‘-CFzBl‘__.._ should, according to the present invention, consist of a From the data listed in the table it can be seen how the ?uorochlorohydrocarbon (having at least one hydrogen mixtures 7, 8 and 9, according to the present invention, atom per molecule) of relatively low toxicity, low ‘boiling _ containing the dilferent brominated Freon (actual extin point, high solubility in the chlorinated Freon and good 20 guishing agents) and a fluorochlorohydrocarbon contain ability to generate chain-reaction-terminating free radicals ing at least one hydrogen atom in the molecule (CFZCIH), by thermal decomposition. The propellant and coadjuvant have flame-extinguishing powers far higher than those ex ?uorinated hydrocarbons should have a carbon number of pected from their composition. one or two, a ?uorine content per molecule of at least More particularly, as we can see from the above men two and at least one hydrogen atom per molecule; ?uorine- 30 tioned values, the efficiency being equal, for the extinguish containing chlorinated hydrocarbons containing at most ing composition according to the present invention a lower one atom of chlorine per molecule are also suitable. Best consumption of brominated Freons is requested, i.e. up results are obtained with coadjuvants such as CFZCIH, to 78%, in comparison with the theoretical consumption. CF3H, CF2H2 and CFZ-CFZH. The brominated Freons are We claim: preferably one or two carbon fully halogenated haloalkanes 35 1. A ?ame-extinguishing composition consisting essen— having at least two ?uorine atoms and at least one bro- tially of at least one completely halogenated alkane se mine atom per molecule. Best results are obtained with lected from the group consisting of CFZBr-CFZBr, CFBBr, CFZCIBr,CF2Br-CF2Br,CF2Br2 and CFEBr. " CF2Br2 and CF2BrCl, and at least one coadjuvant ad While the optimum ratio of the ?uorinated hydrocarbon 40 mixed therewith and selected from the group consisting of to the brominated Freon depends upon the nature of the CF2ClH, CF3H, CF2H-CF2H and CF2H2, the molar ratio particular compound, it has been found that the molar ra- of said coadjuvant to said completely halogenated al tio of the ?uorine-containing hydrocarbon adjuvant to the kane ranging between substantially 0.2 and 5. brominated Freon (bromo?uoro tetrahalomethane or hex- 2. A ?ame-extinguishing composition consisting essen aloethane)
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